Control device of AC rotating machine

ABSTRACT

A control device of an AC rotating machine includes a controller receiving a current vector instruction and a detection current vector as inputs and outputs a voltage vector instruction to the AC rotating machine, an alternating current amplitude computation mechanism computing an alternating current amplitude of at least one of a parallel component and an orthogonal component with respect to the voltage vector instruction, an alternating current amplitude instruction generator generating an alternating current amplitude instruction from the current vector instruction, and a magnetic-pole position computation mechanism computing an estimated magnetic-pole position of the AC rotating machine. The magnetic-pole position computation mechanism computes the estimated magnetic-pole position so that the alternating current amplitude coincides with the alternating current amplitude instruction.

TECHNICAL FIELD

The present invention relates to a control device of an AC rotatingmachine capable of obtaining a rotor position of an AC rotating machine,such as an induction machine and a synchronous machine, without using aposition sensor.

BACKGROUND ART

In the control of an AC rotating machine, a speed sensor or a positionsensor is normally used in order to rotate the rotating machine at adesired output or rotational speed. This method involving attachment ofthese sensors, however, increases the cost and deteriorates performancedue to wiring. Hence, there is a problem that this method isdisadvantageous in fault tolerance and maintenance. To overcome thisproblem, there are proposed methods of detecting a magnetic-poleposition and a rotational speed of the AC rotating machine without usinga sensor.

Of these methods, there is a method using an inductive voltage and thismethod is chiefly advantageous in an operation in a high-speed region inwhich the inductive voltage is high. Meanwhile, for a speed region inwhich it is difficult to use an inductive voltage, such as a zero speedor low speed region, there is a technique of estimating a magnetic-poleposition using saliency of an inductance by superimposing a voltage or acurrent at a frequency different from a fundamental frequency on the ACrotating machine.

For example, the invention described in PTL 1 discloses a method ofestimating a magnetic-pole position by applying a high-frequencyalternating voltage to the AC rotating machine so that an amplitude of ahigh-frequency current flowing in an orthogonal direction of the appliedvoltage becomes 0.

The invention described in PTL 2 discloses an estimation method asfollows. That is, a high-frequency current value obtained by applying ahigh-frequency alternating voltage to the rotating machine istransformed to a d-q axis coordinate with a 45° phase shift from anestimated angle. A magnetic-pole position is then estimated so that thehigh-frequency impedances Zdm and Zqm obtained from the transformationresult coincide with each other. Further, a correction under high loadis made by subtracting a compensation angle θ^r computed by multiplyinga torque component of a current instruction value by a proportionalconstant from the estimated magnetic-pole position. An estimatedposition θ^c is thus computed.

CITATION LIST Patent Literature

PTL 1: Japanese Patent No. 3312472

PTL 2: JP-A-2002-291283

PTL 3: Japanese Patent No. 4672236

SUMMARY OF INVENTION Technical Problem

The invention described in PTL 1 adjusts the axis to which is applied ahigh-frequency alternating voltage so that the amplitude of theorthogonal component in the direction in which to apply thehigh-frequency alternating voltage becomes 0. Accordingly, when theinductance magnetically saturates while a load current is flowing, theestimated position deviates from the actual magnetic-pole position.

Also, the invention described in PTL 2 applies a high-frequencyalternating voltage to the axis such that the high-frequency impedancescoincide with each other. Hence, the axis to which is applied thehigh-frequency alternating voltage and the axis on which no torque isgenerated coincide with each other under no load. However, the axis towhich is applied the high-frequency alternating voltage deviates fromthe axis on which no torque is generated under load, and there is aproblem that such a deviation causes vibrations and noises.

Solution to Problem

A control device of an AC rotating machine of the invention includes:current vector detection means for detecting a current vector of the ACrotating machine; control means for receiving a current vectorinstruction and the detection current vector as inputs and outputting avoltage vector instruction obtained by adding a fundamental voltagevector instruction to drive the AC rotating machine and an alternatingvoltage vector instruction alternating to an arbitrary axis; voltageapplication means for applying a voltage to the AC rotating machineaccording to the voltage vector instruction; alternating currentamplitude computation means for receiving a current vector detected bythe current vector detection means as an input and computing analternating current amplitude of at least one of a parallel componentand an orthogonal component with respect to the alternating voltagevector instruction; alternating current amplitude instruction generationmeans for generating an alternating current amplitude instruction fromthe current vector instruction; and magnetic-pole position computationmeans for computing an estimated magnetic-pole position of the ACrotating machine. The control device is characterized in that themagnetic-pole position computation means computes the estimatedmagnetic-pole position so that the alternating current amplitudecoincides with the alternating current amplitude instruction.

Advantageous Effects of Invention

According to the invention, by computing the estimated position so thatthe alternating current amplitude coincides with the alternating currentamplitude instruction, the magnetic-pole position can be estimated whilea high-frequency alternating voltage applied to estimate a magnetic-poleposition is kept applied always to an axis on which no torque isgenerated. Moreover, because there is no influence of an error of theestimated position caused by magnetic saturation, vibrations and noisesof the rotating machine can be suppressed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a view showing an overall configuration of a control device ofan AC rotating machine of a first embodiment.

FIG. 2 is a schematic configuration view used to describe an internalconfiguration of control means 3 of the first embodiment.

FIG. 3 is a schematic configuration view showing an internalconfiguration of alternating current amplitude computation means 5 ofthe first embodiment.

FIG. 4 is a view used to describe an internal configuration of a filter51 of FIG. 3.

FIG. 5 is a view used to describe an internal configuration of anorthogonal component extraction unit 52 of FIG. 3.

FIG. 6 is a view used to describe an operation of the AC rotatingmachine of the first embodiment by means of vector.

FIG. 7 is a view used to describe an operation of the AC rotatingmachine of the first embodiment by comparing an inductance distributionappearing under load with that under no load.

FIG. 8 is a view used to describe a state of FIG. 7 by means of vector.

FIG. 9 is a view used to describe an operation of PTL 2.

FIG. 10 is a schematic configuration view showing an internalconfiguration of magnetic-pole position computation means 6 of the firstembodiment.

FIG. 11 is a view showing an overall configuration of a control deviceof an AC rotating machine of a second embodiment.

FIG. 12 is a schematic configuration view showing an internalconfiguration of magnetic-pole position computation means 6 of thesecond embodiment.

FIG. 13 is a schematic configuration view showing an internalconfiguration of a deviation amplification portion 64 of the secondembodiment.

FIG. 14 is a schematic configuration view showing another example of theconfiguration of the deviation amplification portion 64 of the secondembodiment.

FIG. 15 is a schematic configuration view showing an internalconfiguration of an adaptive observation portion 65 of the secondembodiment.

FIG. 16 is a schematic configuration view showing an internalconfiguration of a state observation unit 652 of the second embodiment.

FIG. 17 is a view used to describe an operation of the second embodimentby means of vector.

FIG. 18 is a schematic configuration view showing an internalconfiguration of alternating current amplitude computation means 5 ofthe second embodiment.

FIG. 19 is a schematic configuration view showing an internalconfiguration of an alternating amplitude extraction unit 53 of thesecond embodiment.

FIG. 20 is a view showing an overall configuration of a control deviceof an AC rotating machine of a third embodiment.

FIG. 21 is a view showing another example of the configuration of thecontrol device of the AC rotating machine of the third embodiment.

FIG. 22 is a view showing a constant torque curve of an AC rotatingmachine of a fourth embodiment.

FIG. 23 is a view used to describe an operation of the fourthembodiment.

FIG. 24 is a view used to describe an operation of the fourthembodiment.

DESCRIPTION OF EMBODIMENTS

First Embodiment

FIG. 1 is a view showing an overall configuration of a control device ofan AC rotating machine according to a first embodiment of the invention.Referring to the drawing, an AC rotating machine 1 is a synchronousmotor, and herein a synchronous machine using permanent magnets. Thisembodiment will describe a synchronous motor by way of example. Itshould be appreciated, however, that the control device can be alsoformed on the same principle for other types of rotating machine.

Connected to the AC rotating machine 1 are current vector detectionmeans 2 for detecting a current vector of the AC rotating machine 1 andvoltage application means 4 for applying a voltage and corresponding toa power converter, such as an inverter.

The current vector detection means 2 detects currents of three phases,iu, iv, and iw, of the AC rotating machine 1, and applies coordinatetransformation to the detected currents to obtain a current on a d-qaxis known as an orthogonal coordinate rotating in synchronization witha rotor of the AC rotating machine 1 by means of a coordinatetransformer 21 using an estimated magnetic-pole position θ0 describedbelow. The current thus obtained is outputted as a detection currentvector (ids, iqs).

In order to detect currents of three phases, currents of all the threephases may be detected. Alternatively, currents of three phases may befound by detecting currents of two phases on the ground that a sum ofcurrents of three phases is zero. Further, currents of three phases maybe computed on the basis of an inverter bus current or currents flowingthrough switching elements and states of the switching elements.

As is shown in a configuration view of FIG. 2 in detail, the controlmeans 3 subtracts the detection current vector (ids, iqs) from a currentvector instruction (id_ref, iq_ref) given from the outside by means ofan adder-subtractor 31. A current controller 32 outputs a fundamentalvoltage vector instruction (vdf, vqf) by performingproportional-plus-integral control so that there is no deviation betweenthe current vector instruction, which is an output of theadder-subtractor 31, and the detection current vector. A high-frequencyalternating voltage vector generator 33 outputs a high-frequencyalternating voltage vector instruction (vdh, vqh) on the d-q axis.

In this embodiment, vqh=0 is given so that an alternating voltage isapplied to the d-axis direction alone. The adder-subtractor 34 outputs avoltage vector instruction (vd, vq), which is obtained by adding thefundamental voltage vector instruction and the high-frequencyalternating voltage vector instruction. A coordinate transformer 35transforms the voltage vector instruction (vd, vq), which is an outputof the adder-subtractor 34, to a three-phase voltage vector instruction(vu, vv, vw) by transformation from d-q axis to a stationary coordinateusing the estimated position θ0 and outputs the transformation result.

In this embodiment, the control means 3 adopts the method of generatinga voltage instruction vector using the proportional-plus-integralcontrol. It should be appreciated, however, that the control means 3adopting, for example, the V/f control can be also formed on the sameprinciple by adding the high-frequency alternating voltage vectorinstruction.

The voltage application means 4 is a power converter, such as aninverter, and applies a voltage to the AC rotating machine 1 accordingto a voltage vector instruction outputted from the control means 3. Asis shown in a configuration view of FIG. 3 in detail, the alternatingcurrent amplitude computation means 5 extracts a high-frequency currentvector obtained from the detection current vector by means of a filter51, computes an amplitude of an orthogonal component of a high-frequencycurrent by means of an orthogonal component extraction unit 52, andoutputs the computation result as an alternating current amplitude.

The filter 51 is a filter that extracts a high-frequency current vectorfrom a detection current vector and can be of any type of filter as longas the filter is capable of extracting a frequency component same asthat of the high-frequency alternating voltage vector instruction (vdh,vqh) from the detection current vector. For example, as is shown in FIG.4, the high-frequency current vector is extracted using a notch filter511 known as a band-stop filter with a narrow stop-band. The notchfilter 511 of FIG. 4 applies notch filtering to remove an angularfrequency ωh of the high-frequency alternating voltage vector expressedby Equation (1) as below to the detection current vector and removes acomponent of the angular frequency ωh from the detection current vector.An adder-subtractor 512 computes a high-frequency current vector of thecomponent of the angular frequency ωh from the detection current vectorby subtracting an output of the notch filter 511 from the detectioncurrent vector. In Equation (1) below, is a Laplace operator and qx is anotch depth.

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 1} \right\rbrack & \; \\{\frac{s^{2} + \omega_{h}^{2}}{s^{2} + {\frac{\omega_{h}}{q_{x}}s} + \omega_{h}^{2}} =} & (1)\end{matrix}$

FIG. 5 is a view showing a configuration of the orthogonal componentextraction unit 52 of FIG. 3. The orthogonal component extraction unit52 selects only iqh, which is a high-frequency current vector in thedirection orthogonal to the d axis, by multiplying the high-frequencycurrent vector (idh, iqh) by a matrix (0, 1)^(T) by means of anorthogonal component selector 521. An amplitude computation unit 522outputs |iqh|, which is the magnitude (amplitude) of iqh computed inaccordance with Equation (2) as below. In Equation (2) below, T is acycle of iqh.

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 2} \right\rbrack & \; \\{{i_{qh}} = \sqrt{\frac{2}{T}{\int_{0}^{T}{i_{qh}^{2}\ {\mathbb{d}t}}}}} & (2)\end{matrix}$

The above has described the configuration of the alternating currentamplitude computation means 5.

Referring to FIG. 1 again, the magnetic-pole position computation means6 computes an estimated magnetic-pole position according to thealternating current amplitude and an alternating current amplitudeinstruction outputted from the alternating current amplitude instructiongeneration means 7 described below.

Firstly, a method of computing a magnetic-pole position by applying ahigh-frequency alternating voltage will be described. A description isfirst given to a mathematical formula expressing a high-frequencycurrent vector flowing through the AC rotating machine 1 when thehigh-frequency alternating voltage vector generator 33 described aboveoutputs the high-frequency alternating voltage vectors vdh and vqh.

As is shown in FIG. 6, let a dm axis be a rotor flux vector direction, aqm axis be a direction orthogonal to the dm axis, a d axis be adirection indicated by the estimated magnetic-pole position θ0 obtainedby applying the high-frequency alternating voltage vector, and a q axisbe a direction orthogonal to the d axis. Also, let Δθ be a deviationbetween the d axis and the dm axis. FIG. 6 shows a state when the ACrotating machine 1 is under no load and an operation is performed sothat the d axis steadily coincides with the dm axis. FIG. 6 is a viewshowing a case where a deviation Δθ is generated instantaneously. Inthis instance, a mathematical formula of the AC rotating machine 1 whenthe high-frequency alternating voltage vectors vdh and vqh are appliedto the d axis and the q axis, respectively, is expressed by Equation (3)as below. In the equation, P is a differential operator.

$\begin{matrix}{\mspace{79mu}\left\lbrack {{Math}.\mspace{14mu} 3} \right\rbrack} & \; \\{{\begin{bmatrix}v_{dh} \\v_{qh}\end{bmatrix} = {{\begin{bmatrix}{R + {pL}_{dc} - {\omega_{r}L_{dqc}}} & {{pL}_{dqc} - {\omega_{r}L_{qc}}} \\{{pL}_{dqc} - {\omega_{r}L_{qc}}} & {R + {pL}_{dc} - {\omega_{r}L_{dqc}}}\end{bmatrix}\begin{bmatrix}i_{dh} \\i_{qh}\end{bmatrix}} + {\omega_{r}{\phi_{j}\begin{bmatrix}{{- \sin}\;{\Delta\theta}} \\{\cos\;{\Delta\theta}}\end{bmatrix}}}}}\mspace{20mu}{{{where}\mspace{20mu}\begin{pmatrix}{{L_{dc} = {L - {l\;\cos\; 2{\Delta\theta}}}},{L_{qc} = {L + {l\;\cos\; 2\Delta}}}} \\{L_{dqc} = {l\;\sin\; 2{\Delta\theta}}} \\{{L = \frac{L_{d} + L_{q}}{2}},{l = \frac{L_{q} - L_{d}}{2}}}\end{pmatrix}},}} & (3)\end{matrix}$R is a stator winding resistance of the AC rotating machine 1, L_(d) isan inductance in the dm-axis direction, L_(q) is an inductance in theqm-axis direction, Δθ is a deviation between the position of the dm axisand the position of the d axis, ω_(r) is a rotational speed, φ_(f) isthe magnitude of the rotor flux vector, i_(dh) is a d-axishigh-frequency current, and i_(qh) is a q-axis high-frequency current.

In a case where the magnetic-pole position is detected using ahigh-frequency alternating voltage, a high speed region isdisadvantageous in terms of operation efficiency, a voltage utilizationratio, and a maximum current because a voltage and a current at a highfrequency are generated. It is therefore preferable to use thehigh-frequency alternating voltage at a zero speed or a low speed. Also,it is preferable to employ magnetic-pole position detection means usinga known adaptive observation unit in the high speed region. Such beingthe case, assume herein that a high-frequency voltage is used at a zerospeed to a low speed. Then, given rotational speed ωr≈0, we obtainEquation (4) as below from Equation (3) above.

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 4} \right\rbrack & \; \\{\begin{bmatrix}v_{dh} \\v_{qh}\end{bmatrix} = {{R\begin{bmatrix}i_{dh} \\i_{qh}\end{bmatrix}} + {{p\begin{bmatrix}L_{dc} & L_{dqc} \\L_{dqc} & L_{qc}\end{bmatrix}}\begin{bmatrix}i_{dh} \\i_{qh}\end{bmatrix}}}} & (4)\end{matrix}$

Further, the right-hand second term is a differential of thehigh-frequency current. Because the differential of the high-frequencycurrent is increased by a factor of the angular frequency ωh of thehigh-frequency voltage, we obtain, right-hand second term>>right-handfirst term, and therefore the right-hand first term can be disregarded.Consequently, Equation (5) as below can be obtained.

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 5} \right\rbrack & \; \\{{p\begin{bmatrix}i_{dh} \\i_{qh}\end{bmatrix}} = {{\frac{1}{L^{2} - l^{2}}\begin{bmatrix}{L + {l\;\cos\; 2{\Delta\theta}}} & {{- l}\;\sin\; 2{\Delta\theta}} \\{{- l}\;\sin\; 2{\Delta\theta}} & {L - {l\;\cos\; 2{\Delta\theta}}}\end{bmatrix}}\begin{bmatrix}v_{dh} \\v_{qh}\end{bmatrix}}} & (5)\end{matrix}$

Assume that high-frequency voltage vector is given by Equation (6) asbelow. Then, by substituting Equation (6) below into Equation (5) aboveand integrating the both sides, the high-frequency current vectors idhand iqh are expressed by Equation (7) as below.

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 6} \right\rbrack & \; \\{{v_{dh} = {{Vh}\;\sin\;\omega_{h}t}}{v_{qh} = 0}} & (6) \\\left\lbrack {{Math}.\mspace{14mu} 7} \right\rbrack & \; \\\begin{matrix}{\begin{bmatrix}i_{dh} \\i_{qh}\end{bmatrix} = {{\frac{- V_{h}}{\omega_{h}\left( {L^{2} - l^{2}} \right)}\begin{bmatrix}{L + {l\;\cos\; 2\;\Delta\;\theta}} & {{- l}\;\sin\; 2\;\Delta\;\theta} \\{{- l}\;\sin\; 2\;\Delta\;\theta} & {L - {l\;\cos\; 2\;\Delta\;\theta}}\end{bmatrix}}\begin{bmatrix}{\cos\;\omega_{h}t} \\0\end{bmatrix}}} \\{= {{\frac{- V_{h}}{\omega_{h}\left( {L^{2} - l^{2}} \right)}\begin{bmatrix}{L + {l\;\cos\; 2\;\Delta\;\theta}} \\{{- l}\;\sin\; 2\;\Delta\;\theta}\end{bmatrix}}\cos\;\omega_{h}t}}\end{matrix} & (7)\end{matrix}$

In order to estimate the magnetic-pole position, θ0 such that thedeviation Δθ becomes 0 is computed. By using an amplitude component ofthe high-frequency current of Equation (7) above, Δθ can be expressed asa function of the current amplitude. Herein, by using the amplitude ofthe orthogonal component iqh, |iqh|, of the high-frequency current,Equation (8) as below can be obtained from Equation (7) above.

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 8} \right\rbrack & \; \\{{i_{qh}} = {\frac{V_{h}l}{\omega_{h}\left( {L^{2} - l^{2}} \right)}\sin\; 2\;\Delta\;\theta}} & (8)\end{matrix}$

Also, Equation (8) can be rewritten to Equation (9) as below withrespect to Δθ.

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 9} \right\rbrack & \; \\{{\Delta\;\theta} = \frac{\sin^{- 1}\left\{ \frac{{i_{qh}}{\omega_{h}\left( {L^{2} - l^{2}} \right)}}{V_{h}l} \right\}}{2}} & (9)\end{matrix}$

It is understood from Equation (9) above that approximating Δθ to zerois equal to approximating |iqh| to zero. Hence, the estimated positionθ0 can be expressed by Equation (10) as below using aproportional-plus-integral unit.

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 10} \right\rbrack & \; \\{\theta_{0} = {\theta_{0} + {{K_{p\;\theta}\left( {1 + \frac{K_{i\;\theta}}{s}} \right)}\left( {0 - {i_{qh}}} \right)}}} & (10)\end{matrix}$

It should be noted that the angular frequency ωh of the high-frequencyvoltage and the high-frequency voltage amplitude Vh can be setarbitrarily in the high-frequency alternating voltage vector generator33 and are therefore known. Also, L and I can be found from Ld and Lq asin where clause of Equation (3) above and Ld and Lq can be found bymeasuring the both in advance. Hence, L and I are also known.

As has been described above, the deviation Δθ from the axis on which thehigh-frequency voltage vector is applied can be computed on the basis of|iqh|.

An error of the estimated position due to inductance magnetic saturationunder load will now be described.

As has been described above, the inductance of the AC rotating machinemagnetically saturates under load. Hence, assume that a position errorθe is generated under a specific load, as is shown in FIG. 7, then, aninductance distribution under the specific load varies by θe from thedistribution under no load. In order to express this variance byEquation (3) above, Ldc, Lqc, and Ldqc are redefined by Equation (11) asfollows.

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 11} \right\rbrack & \; \\\begin{pmatrix}{L_{dc} = {L - {l\;\cos\; 2\left( {{\Delta\;\theta} - \theta_{e}} \right)}}} \\{L_{qc} = {L + {l\;\cos\; 2\left( {{\Delta\;\theta} - \theta_{e}} \right)}}} \\{L_{dqc} = {l\;\sin\; 2\left( {{\Delta\;\theta} - \theta_{e}} \right)}}\end{pmatrix} & (11)\end{matrix}$

By developing Equation (3) above using Equation (11) above, Equation(12) as below can be obtained. Also, the magnitude of the high-frequencycurrent vector iqh, |iqh|, is expressed by Equation (13) as below.

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 12} \right\rbrack & \; \\{\begin{bmatrix}i_{dh} \\i_{qh}\end{bmatrix} = {{\frac{- V_{h}}{\omega_{h}\left( {L^{2} - l^{2}} \right)}\begin{bmatrix}{L + {l\;\cos\; 2\;\left( {{\Delta\;\theta} - \theta_{e}} \right)}} \\{{- l}\;\sin\; 2\left( {{\Delta\;\theta} - \theta_{e}} \right)}\end{bmatrix}}\cos\;\omega_{h}t}} & (12) \\\left\lbrack {{Math}.\mspace{14mu} 13} \right\rbrack & \; \\{{i_{qh}} = {\frac{V_{h}l}{\omega_{h}\left( {L^{2} - l^{2}} \right)}\sin\; 2\left( {{\Delta\;\theta} - \theta_{e}} \right)}} & (13)\end{matrix}$

By forming the proportional-plus-integral unit of Equation (10) above sothat |iqh| approximates to zero, it is understood from Equation (13)above that (Δθ−θe) approximates to zero. More specifically, because Δθconverges to θe, as is shown in FIG. 8, the d axis indicated by theestimated magnetic-pole position θ0 is detected at a position deviatedby θe from the dm axis as the actual magnetic-pole position.

The invention described in PTL 2 makes a compensation for the estimatedmagnetic-pole position using a compensation angle. However, as is shownin FIG. 9, because a high-frequency voltage is applied to an axis suchthat high-frequency impedances of the axes ±45° away from the estimatedmagnetic-pole position θ0 coincide with each other, the axis (d axis) towhich is applied a high-frequency voltage deviates from the axis (dmaxis) on which no torque is generated. Such a deviation becomes a factorof vibrations and noises of the rotating machine due to a torque by ahigh-frequency voltage.

In order to overcome such an inconvenience, the axis to which is appliedthe high-frequency alternating voltage vector is always set to the dmaxis in the computation of the estimated magnetic-pole position by themagnetic-pole position computation means 6, so that the occurrence ofvibrations and noises of the rotating machine due to a torque by ahigh-frequency voltage are suppressed. This means, in short, toapproximate the deviation Δθ between the dm axis, which is the actualmagnetic-pole position, and the d axis, which is the estimatedmagnetic-pole position, to zero. By approximating Δθ to zero in Equation(13), |iqh| is expressed by Equation (14) as follows.

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 14} \right\rbrack & \; \\{{i_{qh}} = {{- \frac{V_{h}l}{\omega_{h}\left( {L^{2} - l^{2}} \right)}}\sin\; 2\theta_{e}}} & (14)\end{matrix}$

That is to say, when the value of |iqh| approximates to a value of theright-hand side of Equation (14) above, Δθ approximates to zero. In thisinstance, because θe is unknown, the right-hand side of Equation (14)above cannot be computed in real time. However, because θe has acharacteristic that it varies with the magnitude of the load current, θecan be measured in advance. Hence, an alternating current amplitudeinstruction |iqh_ref|, which is an output of the alternating currentamplitude instruction generation means 7 described below, is set byEquation (15) as below and the estimated magnetic-pole position θ0 isformed by Equation (16) as below using a proportional-plus-integral unitso that |iqh_ref| coincides with |iqh|. Accordingly, |iqh| can beapproximated to the instruction value |iqh_ref|. Consequently, not onlyby bringing the d axis, which is the estimated magnetic-pole position,into coincidence with the dm axis, but also by setting the dm axis asthe direction to which is applied the high-frequency voltage vector, theoccurrence of vibrations and noises of the rotating machine due to atorque can be suppressed. A setting method of |iqh_ref| will bedescribed below.

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 15} \right\rbrack & \; \\{{{i_{{qh}\_}{ref}}} = {{- \frac{V_{h}l}{\omega_{h}\left( {L^{2} - l^{2}} \right)}}\sin\; 2\theta_{e}}} & (15) \\\left\lbrack {{Math}.\mspace{14mu} 16} \right\rbrack & \; \\{\theta_{0} = {\theta_{0} + {{K_{p\;\theta}\left( {1 + \frac{K_{i\;\theta}}{s}} \right)}\left( {{{i_{{qh}\_}{ref}}} - {i_{qh}}} \right)}}} & (16)\end{matrix}$

The above has described the computation method of the magnetic-poleposition estimation by the magnetic-pole position computation means 6.

A configuration of the magnetic-pole position computation means 6 willnow be described.

As is shown in FIG. 10, the magnetic-pole position computation means 6is formed of an adder-subtractor 61 that outputs a deviation between thealternating current amplitude instruction and the alternating currentamplitude and a magnetic-pole position estimation unit 62 that outputsan estimated magnetic-pole position from the deviation. Themagnetic-pole position estimation unit 62 outputs the estimatedmagnetic-pole position in accordance with Equation (16) above on thebasis of a deviation value inputted therein from the adder-subtractor61. The above has described the configuration of the magnetic-poleposition computation means 6.

Further, the alternating current amplitude instruction generation means7 generates the alternating current amplitude instruction |iqh_ref| bymultiplying the current vector instruction (id_ref, iq_ref) by (Kd,Kq)^(T) (T stands for a transposed matrix), which is a transposed matrixof an amplification value (Kd, Kg). The amplification value (Kd, Kq) cantake a simple constant value. Alternatively, by changing theamplification value (Kd, Kq) according to the current vector instructionusing a table, the AC current amplitude instruction value can be moreaccurate. Also, the alternating current amplitude instruction may begenerated from only a torque component of the current vector instructionby setting as Kd=0.

Regarding the amplification value, the value of |iqh| obtained inaccordance with Equation (2) above when the high-frequency alternatingvoltage vector and the load current are applied to the AC rotatingmachine 1 is measured in advance, and the amplification value isdetermined from the current vector instruction and |iqh|. It thusbecomes possible to find the current amplitude instruction value|iqh_ref| independently of unknown θe. Regarding the measurement, ainstruction value for the current instruction vector may be foundanalytically, for example, by electromagnetic analysis or the value maybe measured using the actual machine. By measuring these values inadvance, these values can be immediately applied to a sensorlessoperation.

As has been described above, according to the configuration of thisembodiment, because it becomes possible to apply the alternating voltagealways to the axis on which no torque is generated using the estimatedmagnetic-pole position θ0 by applying the high-frequency alternatingvoltage vector so that the alternating current amplitude coincides withthe alternating current amplitude instruction, vibrations and noises ofthe rotating machine can be suppressed.

Second Embodiment

The first embodiment above has described the method of estimating themagnetic-pole position using a high-frequency voltage without generatinga magnetic-pole position error even under load. With this method,however, giving a high-frequency voltage in a high speed region isdisadvantageous in terms of operation efficiency, a voltage utilizationratio, and a maximum current as has been described above.

In a second embodiment, the magnetic-pole position computation means 6has an adaptive observation unit 65 in order to estimate themagnetic-pole position in all of the speed regions from a low speed to ahigh speed, and the magnetic-pole position is computed using theadaptive observation unit 65 in all of the speed regions. Among thespeed regions, a low speed region is a region in which an inductivevoltage is so small that it is difficult to compute a flux vector.Accordingly, a flux vector is computed using a high-frequencyalternating voltage, so that compensation is made for the magnetic-poleposition estimation in the low speed region in which the adaptiveobservation unit 65 is disadvantageous. It thus becomes possible toestimate the magnetic-pole position in all of the speed regions.

FIG. 11 shows an overall configuration of a control device of an ACrotating machine according to the second embodiment of the invention. Inthis embodiment, the alternating current amplitude, alternating currentamplitude instruction, the voltage instruction vector, and the detectioncurrent vector are inputted into the magnetic-pole position computationmeans 6. The rest is the same as the configuration of the firstembodiment above and a description is omitted herein. FIG. 12 shows aconfiguration of the magnetic-pole position computation means 6 of thisembodiment.

In this embodiment, the magnetic-pole position computation means 6 has aflux vector detection portion 66 that detects a rotor flux vector fromthe alternating current amplitude instruction and the alternatingcurrent amplitude and outputs the detection result as a detection fluxvector, a deviation vector computation portion 63 that outputs a currentdeviation vector, which is a deviation between an estimated currentvector and the detection current vector, and a flux deviation vector,which is a deviation between an estimated flux vector and the detectionflux vector, a deviation amplification portion 64 that amplifies thecurrent deviation vector and the flux deviation vector and outputs theresult as an amplified deviation vector, and the adaptive observationportion 65 that outputs an estimated current vector, an estimated fluxvector, and an estimated magnetic-pole position of the AC rotatingmachine 1.

The deviation vector computation portion 63 outputs a current deviationvector (eids, eiqs) obtained by subtracting a detection current vector(ids, iqs), which is an output of the current vector detection means 2,from an estimated current vector (ids0, iqs0), which is an output of theadaptive observation portion 65 described below by means of anadder-subtractor 631, and outputs a flux deviation vector (eφdr, eθqr)obtained by subtracting a detection flux vector (φdrD, φqrD), which isan output of the flux vector detection portion 66 described below, froman estimated flux vector (φdr0, φqr0), which is an output of theadaptive observation portion 65 described below by means of anadder-subtractor 632.

FIG. 13 is a view showing a configuration of the deviation amplificationportion 64. A gain matrix 641 of FIG. 13 outputs a result obtained bymultiplying (eids, eiqs)^(T), which is a transposed matrix of thecurrent deviation vector (eids, eiqs), by a matrix Hc, and a gain matrix642 outputs a result obtained by multiplying the flux deviation vector(eφdr, eφqr)^(T) by a matrix Hf. The matrices Hc and Hf are gainmatrices defined by Equation (17) as below, and h11 through h44 inEquation (17) below are amplification gains. Herein, h11 through h44 arevalues that can be set arbitrarily. For example, h11 through h42 in thematrix Hc are set so that values of the respective amplification gainsare changed with an estimated speed ωr0 as is set forth in FIG. 9 of PTL3 (Japanese Patent No. 4672236). Likewise, values of h13 through h44 ofthe gain matrix Hf may be set so that values of the respectiveamplification gains are changed with the estimated speed ωr0. In thiscase, as is shown in FIG. 14, it is configured in such a manner that theestimated speed ωr0 is also outputted from the adaptive observationportion 65 described below so that the estimated speed ωr0 is inputtedto the gain matrices 644 and 645 in the deviation amplification portion64.

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 17} \right\rbrack & \; \\{{{Hc} = \begin{pmatrix}h_{11} & h_{12} \\h_{21} & h_{22} \\h_{31} & h_{32} \\h_{41} & h_{42}\end{pmatrix}},{{Hf} = \begin{pmatrix}h_{13} & h_{14} \\h_{23} & h_{24} \\h_{33} & h_{34} \\h_{43} & h_{44}\end{pmatrix}}} & (17)\end{matrix}$

An adder-subtractor 643 outputs an amplified deviation vector (e1, e2,e3, e4)^(T) by adding output vectors of the gain matrix 641 and the gainmatrix 642 of FIG. 13 or output vectors of the gain matrix 644 and thegain matrix 645 of FIG. 14.

Regarding the estimated speed and the estimated magnetic-pole positionoutputted from the adaptive observation portion 65 described below,because a speed and a position can be estimated satisfactorily at highrotations without using a flux deviation vector, which is a deviationbetween the detection flux vector and the estimated flux vector, in acase where an absolute value of the estimated speed is large, values ofh13 through h44 in the gain matrix 642 or the gain matrix 645 are set tozero, so that an output of the gain matrix 642 or the gain matrix 645becomes zero in a high rotation range. Consequently, an amount ofcomputation can be reduced by stopping a computation by the flux vectordetection portion 66. Also, because no high-frequency current isgenerated by vdh and vqh by making outputs of vdh and vqh from thehigh-frequency voltage vector generator 33 inside the control means 3zero, a loss caused by a high-frequency current can be eliminated.

The adaptive observation portion 65 is, as is shown in FIG. 15, formedof a coordinate transformer 651, a state observation unit 652, and anintegration unit 853.

An operation of the adaptive observation portion 65 is described first.Let R be an armature resistance of the AC rotating machine 1, Ld be anarmature inductance in the d-axis direction, Lq be an armatureinductance in the q-axis direction, ωr0 be an estimated speed, and ω bean power-supply angular frequency. Then, matrices A, B, C, D, C1, and C2are defined by Equation (18) as follows.

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 18} \right\rbrack & \; \\{{A = \begin{pmatrix}{- \frac{R}{L_{d}}} & \omega & 0 & {\omega\; r\; 0} \\{- \omega} & {- \frac{R}{L_{q}}} & {{- \omega}\; r\; 0} & 0 \\0 & 0 & 0 & {\omega - {\omega\; r\; 0}} \\0 & 0 & {{- \omega} + {\omega\; r\; 0}} & 0\end{pmatrix}},{B = \begin{pmatrix}1 & 0 \\0 & 1 \\0 & 0 \\0 & 0\end{pmatrix}},{{C\; 1} = \begin{pmatrix}\frac{1}{Ld} & 0 & 0 & 0 \\0 & \frac{1}{Lq} & 0 & 0\end{pmatrix}},{{C\; 2} = \begin{pmatrix}0 & 0 & 1 & 0 \\0 & 0 & 0 & 1\end{pmatrix}}} & (18)\end{matrix}$

Also, let φds0 and φqs0 be a d-axis component and a q-axis component,respectively, of an estimated armature reaction vector on the d-q axis,and vds and vqs be a d-axis component and a q-axis component,respectively, of a voltage instruction vector on the d-q axis. Then, theestimated armature reaction vectors φds0 and φqs0 and the estimated fluxvectors φdr0 and  qr0 can be obtained in accordance with Equation (19)as follows.

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 19} \right\rbrack & \; \\{{\frac{\mathbb{d}\;}{\mathbb{d}t}\begin{pmatrix}{\phi\;{ds}\; 0} \\{\phi\; q\; s\; 0} \\{\phi\;{dr}\; 0} \\{\phi\; q\; r\; 0}\end{pmatrix}} = {{A\begin{pmatrix}{\phi\;{ds}\; 0} \\{\phi\; q\; s\; 0} \\{\phi\;{dr}\; 0} \\{\phi\; q\; r\; 0}\end{pmatrix}} + {B\begin{pmatrix}{vds} \\{vqs}\end{pmatrix}} - \begin{pmatrix}{e\; 1} \\{e\; 2} \\{e\; 3} \\{e\; 4}\end{pmatrix}}} & (19)\end{matrix}$

Also, let s be a Laplace operator (differential operator), kp be aproportional gain, and ki be an integral gain. Then, the estimated speedωr0, which is an internal parameter of the matrix A in Equation (18)above, can be given by Equation (20) as below using current deviationvectors Δids and Δiqs and the estimated flux vectors φdr0 and φqr0.

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 20} \right\rbrack & \; \\{{\omega\; r\; 0} = {\left( {{kp} + \frac{ki}{s}} \right)\left( {{{eiqs}\;\phi\;{dr}\; 0} - {{eids}\;\phi\;{qr}\; 0}} \right)}} & (20)\end{matrix}$

The estimated position θ0 can be obtained by integrating the estimatedspeed in accordance with Equation (21) as follows.

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 21} \right\rbrack & \; \\{{\theta\; 0} = \frac{\omega\; r\; 0}{s}} & (21)\end{matrix}$

Also, the estimated current vectors ids0 and iqs0 can be found inaccordance with Equation (22) as follows.

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 22} \right\rbrack & \; \\{\begin{pmatrix}{{ids}\; 0} \\{{iqs}\; 0}\end{pmatrix} = {C\; 1\begin{pmatrix}{\phi\;{ds}\; 0} \\{\phi\; q\; s\; 0} \\{\phi\;{dr}\; 0} \\{\phi\; q\; r\; 0}\end{pmatrix}}} & (22)\end{matrix}$

Likewise, the estimated flux vectors φdr0 and φqr0 can be found inaccordance with Equation (23) as follows.

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 23} \right\rbrack & \; \\{\begin{pmatrix}{\phi\;{dr}\; 0} \\{\phi\;{qr}\; 0}\end{pmatrix} = {C\; 2\begin{pmatrix}{\phi\;{ds}\; 0} \\{\phi\; q\; s\; 0} \\{\phi\;{dr}\; 0} \\{\phi\; q\; r\; 0}\end{pmatrix}}} & (23)\end{matrix}$

As has been described above, the estimated position, the estimatedcurrent vector, and the estimated flux vector can be calculated inaccordance with Equations (10) through (23) above on the basis of thevoltage instruction vector, the amplification deviation vector, and thecurrent deviation vector.

In view of the foregoing, a description will now be given to FIG. 15 asa view showing a configuration of the adaptive observation portion 65.

Referring to FIG. 15, a coordinate transformer 651 transforms athree-phase AC voltage instruction vector, which is an output of controlmeans, to voltage instruction vectors vds and vqs on the d-q axis, whichis an orthogonal rotating coordinate, and outputs the result to a stateobservation unit 652.

The state observation unit 652, a detail of which is shown in FIG. 16,outputs a result obtained by multiplying a voltage instruction vector(vds, vqs)^(T), which is an output of the coordinate transformer 651, bythe matrix B by means of a gain matrix computation unit 6521. Anadder-subtractor 6522 outputs a vector as a result of addition orsubtraction of an output of the gain matrix computation unit 6521, anoutput of a gain matrix computation unit 6523, and the deviationamplification vector (e1, e2, e3, e4)^(T). An integration unit 6524integrates a vector outputted from the adder-subtractor 6522 on anelement-by-element basis and outputs the result as a vector (φds0, φqs0,φdr0, φqr0)^(T). The description above is the part corresponding to theright-hand side of Equation (19) above. The left-hand side of Equation(19) above corresponds to an input part of the integration unit 6524.

A gain matrix computation unit 6525 outputs an estimated current vector(φds0, φqs0)^(T) by multiplying the vector (φds0, φqs0, φdr0, φqr0)^(T)by the matrix C1. This part corresponds to Equation (22) above. A gainmatrix computation unit 6526 outputs an estimated flux vector (φdr0,φqr0)^(T) by multiplying the vector (φds0, φqs0, φdr0, φqr0)^(T) by thematrix C2. This part corresponds to Equation (23) above.

An integration unit 653 of FIG. 15 finds an estimated position θ0 byintegrating the estimated speed ωr0, which is an output of the stateobservation unit 652, as expressed by Equation (21) above.

The above has described an operation of the adaptive observation portion65.

As has been described, the flux vector detection portion 66 computes thedetection flux vector from the alternating current amplitude and thealternating current amplitude instruction, and the detection flux vectoris described first.

As is shown in FIG. 17, the rotor flux vector φr is in the samedirection as the dm axis. Herein, the rotor flux vector φr is projectedto φdrD in a direction parallel to the high-frequency voltage vector,that is, in the d-axis direction, and to φqrD in a direction orthogonalto the high-frequency voltage vector, that is, in the q-axis direction.Given that φdrD and φqrD projected on the d axis and the q axis,respectively, are detection flux vectors. Then, the detection fluxvectors can be written in a mathematical formula expressed by Equation(24) as follows.

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 24} \right\rbrack & \; \\{\begin{matrix}{{\phi\;{drD}} = {{{\Phi\; r}}\cos\;\Delta\;\theta}} \\{= {\phi_{f}\cos\;\Delta\;\theta}}\end{matrix}\begin{matrix}{{\phi\;{qrD}} = {{{\Phi\; r}}\sin\;\Delta\;\theta}} \\{= {\phi_{f}\sin\;\Delta\;\theta}}\end{matrix}} & (24)\end{matrix}$

Herein, φf in Equation (24) above is the magnitude of the rotor fluxvector φr and can be measured in advance. Hence, in order to compute thedetection flux vector in accordance with Equation (24) above, it issufficient to find Δθ.

In the first embodiment above, a deviation Δθ between the dm axis as therotor flux direction and the d axis as the estimated magnetic-poleposition is expressed by Equation (9) above. Because the adaptiveobservation portion 65 operates so that Δθ steadily approximates tozero, we obtain 2Δθ≈0 and hence sin 2Δθ≈2Δθ. Accordingly, Equation (25)as below can be obtained from Equation (9) above.

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 25} \right\rbrack & \; \\{{\Delta\;\theta} = \frac{{i_{qh}}{\omega_{h}\left( {L^{2} - l^{2}} \right)}}{2\; V_{h}l}} & (25)\end{matrix}$

Hence, the detection flux vector can be computed in accordance withEquations (24) and (25) above using |iqh|.

An operation under load will now be considered. The above has describedthat an inductance distribution under load varies with a load currentand an error is generated between the d axis indicated by the estimatedmagnetic-pole position and the dm axis in the rotor flux direction, sothat Equation (8) above changes to Equation (13) above. Herein, Equation(13) is developed to Equation (26) as follows.

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 26} \right\rbrack & \; \\{{i_{qh}} = {\frac{V_{h}l}{\omega_{h}\left( {L^{2} - l^{2}} \right)}\left\{ {{\sin\; 2\;\Delta\;\theta\;\cos\; 2\;\theta_{e}} - {\cos\; 2\;\Delta\;\theta\;\sin\; 2\;\theta_{e}}} \right\}}} & (26)\end{matrix}$

Assume that an operation is performed so that Δθ steadily becomes zero,then we obtain 2Δθ≈0. Hence, given sin 2Δθ≈2Δθ and cos 2Δθ≈1, Equation(27) as below can be obtained from Equation (26) above.

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 27} \right\rbrack & \; \\{{i_{qh}} = {{\frac{V_{h}l}{\omega_{h}\left( {L^{2} - l^{2}} \right)}2\;\Delta\;\theta\;\cos\; 2\;\theta_{e}} - {\frac{V_{h}l}{\omega_{h}\left( {L^{2} - l^{2}} \right)}\sin\; 2\;\theta_{e}}}} & (27)\end{matrix}$

Herein, the right-hand second term of Equation (27) above is equal toEquation (15) above. Hence, Equation (28) as below is obtained bysubtracting Equation (27) above from Equation (15) above.

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 28} \right\rbrack & \; \\{{{{i_{{qh}\_}{ref}}} - {i_{qh}}} = {2\;\Delta\;\theta\;\cos\; 2\;\theta_{e}\frac{{- V_{h}}l}{\omega_{h}\left( {L^{2} - l^{2}} \right)}}} & (28)\end{matrix}$

Equation (29) with respect to Δθ as below can be obtained from Equation(28) above.

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 29} \right\rbrack & \; \\{{\Delta\;\theta\;\cos\; 2\;\theta_{e}} = {\frac{- {\omega_{h}\left( {L^{2} - l^{2}} \right)}}{2\; V_{h}l}\left( {{{i_{{qh}\_}{ref}}} - {i_{qh}}} \right)}} & (29)\end{matrix}$

Because an unknown value cos 2θe is left in Equation (29), this equationcannot be applied to Equation (24) above intact.

Accordingly, cos 2θe is computed using a parallel component idh of ahigh-frequency current. The parallel component idh of a high-frequencycurrent is expressed by Equation (30) as below from Equation (12) aboveand the magnitude (amplitude) |idh| is expressed by Equation (31) asbelow.

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 30} \right\rbrack & \; \\{i_{dh} = {\frac{- {V_{h}\left( {L + {l\;\cos\; 2\left( {{\Delta\;\theta} - \theta_{e}} \right)}} \right)}}{\omega_{h}\left( {L^{2} - l^{2}} \right)}\cos\;\omega_{h}t}} & (30) \\\left\lbrack {{Math}.\mspace{14mu} 31} \right\rbrack & \; \\{{i_{dh}} = {{- \frac{V_{h}L}{\omega_{h}\left( {L^{2} - l^{2}} \right)}} - {\frac{V_{h}l}{\omega_{h}\left( {L^{2} - l^{2}} \right)}\cos\; 2\left( {{\Delta\;\theta} - \theta_{e}} \right)}}} & (31)\end{matrix}$

Assume that an operation is performed so that Δθ steadily becomes zero,Equation (32) as below is obtained from Δθ≈0,

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 32} \right\rbrack & \; \\{{i_{dh}} = {{- \frac{V_{h}L}{\omega_{h}\left( {L^{2} - l^{2}} \right)}} - {\frac{V_{h}l}{\omega_{h}\left( {L^{2} - l^{2}} \right)}\cos\; 2\;\theta_{e}}}} & (32)\end{matrix}$

The right-hand side of Equation (32) above is known except for cos 2θeand |idh| can be computed from a high-frequency component of thedetection current vector as with |iqh|. That is, cos 2θe can be computedonline in accordance with Equation (33) as follows.

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 33} \right\rbrack & \; \\{{\cos\; 2\;\theta_{e}} = {{{- \frac{\omega_{h}\left( {L^{2} - l^{2}} \right)}{V_{h}l}}{i_{dh}}} - \frac{L}{l}}} & (33)\end{matrix}$

Hence, the detection flux vector expressed by Equation (24) above can becomputed by computing Δθ in accordance with Equations (29) and (33)above.

In this case, as is shown in FIG. 18, the alternating current amplitudecomputation means 5 outputs an alternating current amplitude matrix(|idh|, |iqh|) from the high-frequency current vector by means of analternating amplitude extraction unit 53. As is shown in FIG. 19, thealternating amplitude extraction unit 53 has a parallel componentselector 533 in addition to the orthogonal component selector 531 andthe amplitude computation unit 532. The parallel component selector 533selects idh by multiplying the high-frequency current vector by (1,0)^(T). The amplitude computation unit 532 calculates the amplitude|idh| in accordance with Equation (34) above.

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 34} \right\rbrack & \; \\{{i_{dh}} = \sqrt{\frac{2}{T}{\int_{0}^{T}{i_{dh}^{2}\ {\mathbb{d}t}}}}} & (34)\end{matrix}$

Owing to the configuration as above, a deviation Δθ between the dm axisas the rotor flux direction and the d axis as the estimatedmagnetic-pole position can be computed from the high-frequency currentamplitude and the high-frequency current amplitude instruction. Hence,the detection flux vector can be computed without the need topreliminarily find the magnetic-pole position and an amount ofcomputation can be therefore reduced.

Also, even in an operation under load in which an error appears in theestimated magnetic-pole position, by finding the detection flux vectorfrom the alternating current amplitude and the alternating currentamplitude instruction, finding the flux deviation vector, which is adeviation between the detection flux vector and the estimated fluxvector, and finding a current deviation vector, which is a deviationbetween the detection current vector and the estimated current vector,so that the magnetic-pole position is estimated by the adaptiveobservation portion 65 from the amplified deviation vector obtained byamplifying the flux deviation vector, the magnetic-pole position can beestimated in all of the speed regions without influences of aload-induced error in estimation of the magnetic-pole position.

Third Embodiment

In the first embodiment above, the alternating current amplitudeinstruction generation means 7 generates the alternating currentamplitude instruction from the current vector instruction. The detectioncurrent vector of the AC rotating machine 1 is controlled by the controlmeans 3 so as to steadily coincide with the current vector instruction.Hence, the alternating current amplitude instruction may be generatedfrom the detection current vector.

FIG. 20 shows a configuration of a control device of an AC rotatingmachine of this embodiment. Referring to FIG. 20, the alternatingcurrent amplitude instruction generation means 7 generates thealternating current amplitude instruction from the detection currentvector. The rest is the same as the configuration of the firstembodiment above.

The alternating current amplitude instruction generation means 7generates the alternating current amplitude instruction by multiplyingthe detection current vector (ids, iqs) by an amplification value (Kd,Kq)^(T). The amplification value (Kd, Kq) can take a simple constantvalue or have a table value according to the current vector instruction,in which case the AC current amplitude instruction value can be moreaccurate. Also, by setting as Kd=0, the alternating current instructionmay be generated from only a torque component of the detection currentvector.

As has been described above, the alternating current amplitudeinstruction generation means 7 can compute the magnetic-pole positionusing the alternating current amplitude instruction coinciding with aninternal state of the AC rotating machine by generating the alternatingcurrent amplitude instruction using the detection current vector.

It should be appreciated that the alternating current amplitudeinstruction generation means 7 described in the third embodiment is alsoapplicable in the second embodiment above. In such a case, theconfiguration is as shown in FIG. 21 and the alternating currentamplitude instruction generation means 7 is formed in the same manner asin the third embodiment.

Fourth Embodiment

The control devices of the AC rotating machine according to the firstthrough third embodiments apply a high-frequency voltage in the dm-axisdirection, which is a rotor flux of the AC rotating machine. However, inan AC rotating machine in which a ratio of Ld and Lq (hereinafter,referred to as the saliency ratio) is large, the axis that suppressesthe occurrence of a torque by a high-frequency voltage is not limited tothe dm axis.

This embodiment will describe a control device of an AC rotating machineconfigured to apply a high-frequency voltage in a direction in which theoccurrence of a torque by a high-frequency alternating voltage issuppressed even for an AC rotating machine having a large saliencyratio.

A description is first given to a cause of the occurrence of a torque bya high-frequency alternating voltage and a method of suppressing theoccurrence of a torque.

In a case where the AC rotating machine 1 is a synchronous machine usingpermanent magnets, a generated torque T is known to be expressed byEquation (35) as follows.

[Math. 35]τ=P _(m){φ−(L _(q) −L _(d))i _(d) }i _(q)  (35)where Pm is the number of pole pairs of the AC rotating machine 1, i_(d)is a current in the dm-axis direction, and i_(q) is a current in theqm-axis direction.

By modifying Equation (35) above to Equation (36) as below and giving aconstant value to the torque τ, iq can be expressed as a hyperbolic lineof id. A locus (constant torque curve) of a current vector on the (id,iq) axis in this instance is the one as shown in FIG. 22.

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 36} \right\rbrack & \; \\{i_{q} = \frac{\tau}{P_{m}\left\{ {\phi - {\left( {L_{q} - L_{d}} \right)i_{d}}} \right\}}} & (36)\end{matrix}$

The constant torque curve referred to herein means that a torque isconstant at any current value on the curve and the torque does not varyeven when a current vector moves on the curve. In other words, when thecurrent vector fluctuating with a high-frequency alternating voltage ison this curve, a torque by the high-frequency alternating voltage is notgenerated.

Assume that a fundamental current vector is applied so as to drive theAC rotating machine 1 and a torque is generated. Then, there is aconstant torque curve of this torque. In this instance, when ahigh-frequency alternating voltage is applied in the dm-axis direction,the locus of the high-frequency current vector is the high-frequencycurrent vector shown in FIG. 23. Because this vector locus is not on theconstant torque curve, a torque varies. Accordingly, vibrations andnoises may possibly be generated in the rotating machine.

In order to overcome this inconvenience, by approximating the vectorlocus of the high-frequency current to a tangential line to the constanttorque curve as is shown in FIG. 24, a variance of a torque by thehigh-frequency current vector can be suppressed. By differentiatingEquation (36) above with id, an inclination of the tangential line isobtained in accordance with Equation (37) as below. Further, theinclination can be expressed by Equation (38) as below by modifyingEquation (37) below using Equation (35) above.

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 37} \right\rbrack & \; \\{\frac{\mathbb{d}i_{q}}{\mathbb{d}i_{d}} = \frac{\tau\left( {L_{q} - L_{d}} \right)}{P_{m}\left\{ {\phi - {\left( {L_{q} - L_{d}} \right)i_{d}}} \right\}^{2}}} & (37) \\\left\lbrack {{Math}.\mspace{14mu} 38} \right\rbrack & \; \\{\frac{\mathbb{d}i_{q}}{\mathbb{d}i_{d}} = \frac{\left( {L_{q} - L_{d}} \right)i_{q}}{\left\{ {\phi - {\left( {L_{q} - L_{d}} \right)i_{d}}} \right\}}} & (38)\end{matrix}$

Also, let η be a deviation between the dm axis and a tangential line tothe constant torque curve, then a deviation η in a given fundamentalcurrent vector (id1, iq1) is expressed by Equation (39) as follows,

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 39} \right\rbrack & \; \\{\eta = {\tan^{- 1}\left( \frac{\left( {L_{q} - L_{d}} \right)i_{q\; 1}}{\phi - {\left( {L_{q} - L_{d}} \right)i_{d\; 1}}} \right)}} & (39)\end{matrix}$

In other words, by applying the high-frequency voltage to an axisdisplaced by η from the dm axis, it becomes possible to suppress theoccurrence of a torque by the high-frequency current vector.

The above has described the cause of the occurrence of a torque by thehigh-frequency voltage and a method of suppressing the occurrence of atorque.

In the first through third embodiments above, the high-frequency voltagevector instruction (vdh, vqh) is merely changed in order to apply ahigh-frequency voltage to an axis η away from the dm axis. To be morespecific, this application can be achieved by giving the high-frequencyvoltage vector instruction expressed by Equation (40) as follows.

[Math. 40]v _(dh) =Vh cos η sin ω_(h) tv _(qh) =Vh sin η sin ω_(h) t  (40)

A method of setting |iqh_ref| in this instance will now be described.

When the high-frequency voltage vector instruction is applied to a dcaxis η away from the dm axis, Δθ in Equation (13) above can be replacedwith (η+Δθ1) using an instantaneous deviation Δθ1 from the dc axis, anda high-frequency current amplitude of the qm axis is expressed byEquation (41) as follows.

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 41} \right\rbrack & \; \\{{i_{qh}} = {\frac{V_{h}l}{\omega_{h}\left( {L^{2} - l^{2}} \right)}\sin\; 2\left( {{\Delta\;\theta_{1}} + \eta - \theta_{e}} \right)}} & (41)\end{matrix}$

Because the instantaneous error Δθ1 converges to zero, Equation (42) asbelow can be obtained eventually.

$\begin{matrix}\left\lbrack {{Math}.\mspace{14mu} 42} \right\rbrack & \; \\{{i_{qh}} = {{- \frac{V_{h}l}{\omega_{h}\left( {L^{2} - l^{2}} \right)}}\sin\; 2\left( {\eta + \theta_{e}} \right)}} & (42)\end{matrix}$

Hence, Equation (42) above is the same as Equation (14) above exceptthat merely (2η) is added to the right-hand sine term and the rest isthe same as the configurations of the first through third embodimentsabove. Accordingly, even a case where a direction in which to apply thehigh-frequency voltage vector instruction is changed from the dm axis isapplicable to the first through third embodiments above by finding|iqh_ref| through electromagnetic analysis or preliminary measurementusing the actual machine. Owing to the configuration as above, thehigh-frequency voltage can be applied to a direction in which theoccurrence of a torque is suppressed.

As has been described above, even in an AC rotating machine with a largesaliency ratio, by setting an axis to which is applied a high-frequencyvoltage in a tangential direction to the constant torque curve,vibrations and noises of the rotating machine due to a torquefluctuation caused by a high-frequency voltage can be suppressed.

Reference Signs List

-   1: AC rotating machine, 2: current vector detection means,-   3: control means, 4: voltage application means,-   5: alternating current amplitude computation means,-   6: magnetic-pole position computation means,-   7: alternating current amplitude instruction generation means,-   21, 35, and 651: coordinate transformer,-   31, 34, 512, 61, 643, 6522: adder-subtractor,-   32: current controller,-   33: high-frequency voltage vector generator, 51: filter,-   52: orthogonal component extraction unit, 511: notch filter,-   521 and 531: orthogonal component selector,-   522, 532, and 534: amplitude computation unit,-   533: parallel component selector,-   62: magnetic-pole position estimation unit,-   63: deviation vector computation unit,-   64: deviation amplification unit,-   65: adaptive observation portion,-   66: flux vector detection portion,-   641, 642, 644, and 645: gain matrix-   652: state observation unit, 653: integration unit,-   6521 and 6523 through 6526: gain matrix computation unit,-   6527: speed estimation unit

The invention claimed is:
 1. A control device of an AC rotating machine,comprising: current vector detection means for detecting a currentvector of the AC rotating machine; control means for receiving a currentvector instruction and the detection current vector as inputs andoutputting a voltage vector instruction obtained by adding a fundamentalvoltage vector instruction to drive the AC rotating machine and analternating voltage vector instruction alternating to an arbitrary axis;voltage application means for applying a voltage to the AC rotatingmachine according to the voltage vector instruction; alternating currentamplitude computation means for receiving a current vector detected bythe current vector detection means as an input and computing analternating current amplitude of at least one of a parallel componentand an orthogonal component with respect to the alternating voltagevector instruction; alternating current amplitude instruction generationmeans for generating an alternating current amplitude instruction fromthe current vector instruction or the detection current vector; andmagnetic-pole position computation means for computing an estimatedmagnetic-pole position of the AC rotating machine, the control devicebeing characterized in that the magnetic-pole position computation meanscomputes the estimated magnetic-pole position so that the alternatingcurrent amplitude coincides with the alternating current amplitudeinstruction.
 2. The control device of an AC rotating machine accordingto claim 1, wherein the control means is formed of: an adder-subtractorthat subtracts the detection current vector from the current vectorinstruction; a current controller that generates the fundamental voltagevector instruction by performing control so that an output of theadder-subtractor has no deviation between the current vector instructionand the detection current vector; an alternating voltage vectorgenerator that generates an alternating voltage vector instruction on ad-q axis; and an adder-subtractor that generates the voltage vectorinstruction by adding the fundamental voltage vector instruction and thealternating voltage vector instruction.
 3. The control device of an ACrotating machine according to claim 2, wherein: the alternating currentamplitude instruction generation means computes the alternating currentamplitude instruction from a torque component of the detection currentvector or the current vector instruction.
 4. The control device of an ACrotating machine according to claim 1, wherein the magnetic-poleposition computation means is formed of: an adder-subtractor thatoutputs a deviation between the alternating current amplitudeinstruction and the alternating current amplitude; and a magnetic-poleposition estimation unit that outputs an estimated magnetic-poleposition from the deviation.
 5. The control device of an AC rotatingmachine according to claim 1, wherein: the alternating currentamplitude, the alternating current amplitude instruction, the voltagevector instruction, and the detection current vector are inputted intothe magnetic-pole position computation means.
 6. The control device ofan AC rotating machine according to claim 1, wherein: the magnetic-poleposition computation means has, a flux vector detection portion thatcomputes a detection flux vector from the alternating current amplitudeand the alternating current amplitude instruction, an adaptiveobservation portion that outputs an estimated current vector, anestimated flux vector, and an estimated magnetic-pole position of the ACrotating machine, a deviation vector computation portion that outputs acurrent deviation vector, which is a deviation between the estimatedcurrent vector and the detection current vector, and a flux deviationvector, which is a deviation between the estimated flux vector and thedetection flux vector, and a deviation amplification portion thatamplifies the current deviation vector and the flux deviation vector andoutputs a result as an amplified deviation vector to the adaptiveobservation portion; and the estimated magnetic-pole position outputtedfrom the adaptive observation portion is computed on the basis of theestimated current vector, the estimated flux vector, the amplifieddeviation vector, and the voltage vector instruction.
 7. The controldevice of an AC rotating machine according to claim 1, wherein: thealternating current amplitude instruction generation means computes thealternating current amplitude instruction from a torque component of thedetection current vector or the current vector instruction.
 8. Thecontrol device of an AC rotating machine according to claim 1, wherein:the alternating voltage vector instruction alternates to an axis onwhich no torque is generated during application.
 9. The control deviceof an AC rotating machine according to claim 8, wherein: when anarbitrary constant torque is generated, the control means performscontrol so that the alternating voltage vector instruction is in atangential direction to a locus of the current vector on a d-q axis.